An electronic paper display is a display device which drives “electronic ink” encapsulated within “microcapsules” for display by an electric field. Electronic ink is a kind of liquid by itself, and can be printed or coated on a surface of a carrier. Electronic ink is formed by suspending both very fine black and white particulates in a transparent liquid. Microcapsule technique is to encapsulate electronic ink in the microcapsules so as to solve the problem of conglomeration of pigment particles.
The particulates contained within the electronic ink are charged, in which the white particulates are positively charged and black particulates are negatively charged. Microcapsules are sandwiched between a transparent electrode plate on the upper side and a bottom electrode plate on the lower side. When a negative voltage is applied on the upper transparent electrode plate, the positively charged white particulates will be attracted to the transparent electrode plate under the effect of the electric field and aggregate there, which makes the transparent electrode plate display white; meanwhile, the negatively charged black particulates are repelled to the bottom electrode plate to hide there under the effect of the electric field formed. When a positive voltage is applied on the upper transparent electrode plate, the movement directions of the black particulates and white particulates are reversed so as to display black at the transparent electrode plate. This is the basic principle of the black-white electronic paper display.
In an electronic paper display, there are mainly two ways for controlling the movement of the black and white particulates. In an electronic paper recording device, the electronic paper is powered by and communicated with an electromagnetic induction unit. When a handwritten input operation is performed on the electronic paper with an electronic stylus, the coordinate of the position of the stylus is detected, and then the vector data corresponding to the coordinate track is sent to the electronic paper as display data for display. In another electronic paper display, a touch screen and a drive circuit are provided. The position being touched on the touch screen is detected by the drive circuit to drive the electronic paper display to display correspondingly.
In summary, the existing electronic paper display achieves the display control of the electronic paper by electromagnetic induction or by complex circuit processing, which gives rise to a complex structure and high costs, wastes electrical energy, and cannot meet the development requirements such as energy saving and environment protection for an electronic paper display.